Do you have 3 sprites with 10 animationframes and 2 private variables?

If not ... that's the way I would do .. the animationframe (0, 1, 2, 3, etc) would be similar to the picture of the the digit. By pressing a button you will add the value to the variable and per code you say "If var = 0 set frame 0" or "if var = 9 set frame 9" ...

If it will be 10 or higher you can add "if var >=10 make -10 and add 1 to var of sprite Nr 2" and the same for the second sprite.